Thermodynamic Database for Alloy Semiconductor Systems.
Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||Tohoku University|
ISHIDA Kiyohito Grad.School of Eng., Dept.of Materials Sci., Professor, 大学院・工学研究科, 教授 (20151368)
HILLERT Mats スウェーデン王立工科大学, 名誉教授
ANSARA Ibrah 仏国ドメイン大学, 化学熱力学研究所, 所長
OHNUMA Ikuo Grad.School of Eng., Dept.of Materials Sci., Research Associate, 大学院・工学研究科, 助手 (20250714)
OHTANI Hiroshi Center for Interdisciplinary Research, Associate Professor, 学際科学研究センター, 助教授 (70176923)
KAINUMA Ryosuke Grad.School of Eng., Dept.of Materials Sci., Associate Professor, 大学院・工学研究科, 助教授 (20202004)
IBRAHIM Nicolas Ansara Thermodynamic Lab., Domaine Univ., Head of Lab.
MATS Hillert Dept.of Materials Sci.& Eng., The Royal Institute of Technology, Professor emeri
|Project Period (FY)
1997 – 1998
Completed(Fiscal Year 1998)
|Budget Amount *help
¥4,900,000 (Direct Cost : ¥4,900,000)
Fiscal Year 1998 : ¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1997 : ¥2,500,000 (Direct Cost : ¥2,500,000)
|Keywords||III-V compound semiconductor / phase diagram / thermodynamic database / opto-electronics / liquid phase epitaxy / vapor phase epitaxy / phase equilibria / strain energy / CALPHAD|
III-V compound semiconductors (III=AI, Ga, In : V=P, As, Sb) have various outstanding properties which can not be obtained by Si semiconductor. Furthermore, mixture of these compounds which is called as III-V crystal alloy semiconductor gives possibilities to control its physical properties arbitrarily such as the band gap energy and the lattice constant by its composition. Therefore, III-V crystal alloy semiconductors are of great significance for opto-electronics and high-speed devices. In order to realize the desirable properties, i.e., to create the crystal alloy with appropriate composition by Liquid Phase Epitaxy (LPE) method under the condition of near phase equilibria, phase diagrams are indispensable for controlling their microstructures and compositions. However, it was reported that a thin epitaxial layer on a substrate exhibited completely different phase equilibria from those of bulk materials, for instance, deviation of equilibrium composition, formation of unexpected pha
ses and so on. In this research, thermodynamic analysis on the phase equilibria of III-V crystal alloy semiconductor was carried out based on the thermodynamic data and experimental results. Then, thermodynamic database has been established for calculating the phase equilibria of both bulk and thin layer materials.
Gibbs energies of the liquid phase and the compound are described by the sub-regular solution approximation and the two-sublattice model respectively. The strain energy was taken into account for calculating the stability of a thin epitaxial layer grown on a substrate.
Thermodynamic parameters of eleven ternary systems have been evaluated and thermodynamic database for III-V alloy semiconductors has been constructed with or without taking account of a strain energy between a epitaxial layer and a substrate. The effect of the strain energy which is caused from the epitaxy between a crystal layer and a substrate can be seen, for instance, when a GaAs-GaSb crystal alloy is grown epitaxially on the (100) plane of lnP substrate. According to the result of calculations, unexpected homogeneous phase appears when its thickness is him and its composition is 5 lmol% GaAs which corresponds to the lattice matching composition. This is in good agreement with the experimental result of LPE by Quillec et al. The results of calculations for various combinations between thin layers and substrates show that phase stability of an epitaxial layer depends on the lattice constant and the crystal orientation of the substrate and on the thickness of the epitaxial layer. Less
Research Output (8results)